The present invention relates to laser beam aligning apparatus. It is particularly useful with respect to manipulatable laser beam apparatus used as laser surgical scalpels, and is therefore described below in connection with that application.
As is well known, a laser beam can be focussed to a very small spot (e.g. 100 microns or less in diameter) to produce an extremely hot concentration of light energy. At laser wavelengths (e.g., 10.6 microns), the laser energy is almost completely absorbed by body tissues, and therefore a focussed laser beam may be used to cut through most types of tissues by burning or vaporizing. One of the important advantages of using a laser beam for this purpose is that it makes clean and fine cuts while minimizing damage to tissues outside the cutting lines. Also, the laser beam readily coagulates capillaries, small veins, and small arteries, thereby minimizing loss of blood and keeping the working area clean. Because of these and other advantages, manipulatable leaser beams are increasingly coming into use as surgical scalpels.
One problem in using laser beams as surgical scalpels is the difficulty in precisely aligning the focussed beam on the spot or along the line of the cut during the time the operation is being performed. This is because of the invisible nature of such beams and also because of the high concentration of energy included in them. Various arrangements have been proposed to solve this problem. One proposed arrangement includes two external light sources that project two light beams which intersect at the focal point of the laser beam. Another proposed arrangement includes a reflector which intersects a portion of the laser beam and transmits it to a sighting member, the field of the sighting member being transposed onto the field of the target as viewed via an eyepiece. Such arrangements, however, are not entirely satisfactory with respect to the precision and the convenience of alignment and manipulation required by a surgeon in performing delicate surgical operations.